1973 Chevrolet Camaro Suspension Install - Project F-Bomb - The Hook

Written
by
David Freiburger
on April 17, 2007 Contributors: Tom NelsonWe Think There's a Remote Chance We Can Get 1,500 hp to the Ground. Here Are the Suspension Tactics for Project F-Bomb, Plus Detroit Speed and Engineering's First Minitub Kit for Second-Gen F-Cars.

Here's the biggest challenge with our F-Bomb project '73 Camaro: suspension. We want too much. The car's life is predicted to include street driving, drag racing, and top-speed racing. We'd be happy if we could squeeze in some open-track time while we're at it. No single chassis setup is gonna do all that perfectly, especially considering the fact that we can crank up 1,500 hp at the flywheel. So what'd we do? We left it stock.

Sorta. We thought long and hard about a custom four-link setup out back, which would be ideal for drag racing, and with a Watt's link or Panhard bar, could work for handling and land-speed racing. But it would be harsh on the street, all the Heim joints would be loud and might wear out often, and it'd be expensive. Ladder bars would be cheaper, but they'd be drag-specific with an even worse ride on the street. Up front, we thought about a conversion to Corvette control arms but decided that the factory second-gen ('70-'81) clip was significantly improved from the first-gen ('67-'69) and did not require such extreme tactics. We figured that stock-concept suspension with quality bolt-on upgrades was going to give us the best overall balance of our performance goals. After all, there are street racers running high 7s on leaf springs and slapper bars. We'll see if we can figure out how that's done. To lend some chance of keeping egg off our faces, we wanted the biggest rubber possible without a Pro Street tub job, so we minitubbed the car for the widest possible slicks.

We haven't had a chance to test all this stuff yet, but we know the car has a killer stance. You'll find out how well it works in a few issues when the car runs for the first time. Meanwhile, come back next month to see the guts of the TCI Pro-X Powerglide trans and the Strange 9-inch rearend.

2/25The stock rear-axle location is not centered in the wheel opening, as you can see here. To run 28- or 30-inch-tall drag tires without them rubbing during speed growth, many racers section the sheetmetal forward of the tire. Instead, we opted to move the axle rearward, centering the tires in the openings.

Rear SuspensionWe wanted leaf springs not only for simplicity and reliability but also because it makes you kind of cool when you can run really fast and claim stock, bolt-on suspension. Our favorite way to do that is with CalTracs bars-a more advanced version of the old traction-bar concept. The design resists rearend rotation-and the resulting movement of the pinion angle-shifting the angle of force through the front spring pivot. To further reduce deflection, the front spring-eye bushing is solid aluminum, and while the solid bushing is not as compliant as a soft bushing for street use, we have not found it too objectionable on other cars we've used with CalTracs bars. Also, the preload on the CalTracs bars is adjustable, or the Force Transfer Link under the leaf springs can be removed to allow more spring movement during street driving. It makes a great street/strip combo. The CalTracs bars are $339 for virtually any leaf-spring application. For the Camaro, we told Calvert we had swapped the shocks to the aft-axle position to get the correct lower spring plates. We also used the Calvert Racing 2-inch-drop rear springs, which are similar to monoleaves but use two separate spring halves that are clamped in the middle.

While John Calvert did not feel it was necessary in this application, we decided to add a rear antiroll bar, just in case it was needed either in dragstrip or handling situations. This torsion-bar-type setup is based on a Dick Miller Suspension kit with custom-fabricated installation and end links by Red Zone.

6/25The front end setup is a model of simplicity, using a one-stop-shopping purchase from PSC. It includes A) Global West G-Series tubular control arms with added caster, B) Optional Del-a-lum bushings, C) 2-inch dropped spindles ($279.95), and D) all-new tie-rod ends and sleeves.

Front SuspensionOne of the advantages of doing a frame-off for a race car is that you get to inspect everything in bare metal, and in doing so, we found a hairy crack in one of our lower control arm mounts. The control arms and brakes were also mismatched side-to-side, telling us the car had probably been hit in the right front at some point. The crack was repaired and the entire subframe squared in the car before all the chassis work began. Aside from that work, the suspension components we used were direct bolt-ons, all from Performance Suspension Components (PSC).

The PSC kit includes Global West (GW) tubular upper and lower control arms, and though GW now offers its TLC-series drag-race only arms, we instead chose the conventional G-Series arms that retain the antiroll-bar tabs in case we ever want to add one to the front of the car; we're currently not using one. We also opted for GW's premium Del-a-lum bushings (nondeflecting Delrin plastic and machined aluminum), bringing the price for all four arms to $1,321.

The GW arms are also available specially made for coilover conversion systems, though on John Calvert's advice, we elected to stick with stock-type coil springs. Calvert says they may be heavier, but they also have more stored energy that can contribute to better dragstrip launches for this application with a heavy nose. Our current front coils are Moroso Trick Springs. We cut a coil off them for stance, and the car currently sits too low to steer. We'll need to fix that before our first track blast, and Calvert advises that we should try to get stock-rate springs that will support the car at an acceptable ride height without having to trim coils.

7/25The entire rear half of the interior needs to be removed for the minitub work. The stock wheeltubs are supported right in the middle by the inner structure of the rear quarter-panels, providing an easy cutline for removing the inner half of the tubs. Miserendino used a plasma cutter to slice a clean line.<BR><BR>

8/25Here's the stock '73 Camaro wheelwell. While these cars accept pretty good meats in stock configuration, the bulge in the inner tub (arrow) keeps you from going whole hog.

DSE Deep TubsMinitubbing is the act of widening a car's rear wheeltubs by moving the inner halves as close as possible to the outer face of the rear framerails. It's allowed in many street-racing sanctioning bodies as long as the framerails are left intact. While minitubbing does not allow as much tire room as a full-on Pro Street tub job, it is less invasive and allows the car's stock floors and trunk to be retained. Also, minitubbing usually keeps the stock outer wheeltubs in place whereas Pro Street fabricated wheeltubs are often butted to the insides of the quarter-panels without being firmly attached by anything but a swipe of seam sealer. This leads to leaks, rattles, and loose quarters. If fabricated tubs are welded to the quarter-panels, it leads to warping either during welding or after the car has made a few brutal dragstrip launches. So, to minimize fabrication and to maximize streetability and handling potential, we elected to minitub the F-Bomb rather than Pro Street it.

The shape of the rear framerails makes the second-generation Camaros and Firebirds some of the most difficult cars to minitub. Detroit Speed & Engineering (DSE) recently released its Deep Tubs to simplify the process, and we got the very first kit to try out. The installation was handled by Nick Miserendino at Red Zone Race Fab, the same shop that did all the rollcage work seen in the March '07 issue. The DSE minitub kit includes the stamped Deep Tubs, new fabricated front spring perches, an upper shock crossmember with mounts, offset shackles, leaf-spring pads for the rear axle, lower shock plates and U-bolts, Delrin spring bushings, and filler panels for areas of the stock framerails that need to be cut out with the provided templates. An instructional DVD is included, though we strongly suggest buying it first to make sure you understand the work you're getting into. The base kit is $1,699, or you can get one with shocks and 2-inch- or 3-inch-drop springs for $2,294.

18/25The double-adjustable Stocker Stars by QA1.

ShocksWe've used QA1 Stocker Star adjustable shocks in the past and have been very happy with them, so we're really excited to try the newest in the line: double-adjustable versions. While the originals were 12-way adjustable, these new ones have 24 compression settings and 24 rebound settings for 576 possible valving combos. Being able to set compression and rebound resistance totally independent of each other will be a huge boon to the multipurpose goals of this car. We'll share the tuning process with you once the car is on the track.

With the DSE minitub kit, eyelet/eyelet-style shocks are required in the rear rather than eyelet/stud-style.

The double-adjustable Stocker Stars bolt in to stock locations and feature 5/8-inch-diameter, centerless-ground, hard-chromed piston shafts and bright-anodized, forged-aluminum bodies. They are rebuildable by QA1 and sell for about $300 each. The single-adjustable versions are roughly half that price.

19/25For this application, the front Wilwood disc-brake kit requires that the caliper-mounting tabs be mostly removed from the stock spindles, which Nelson Supercars handled on the mill so this Wilwood bracket could be bolted in place. A template is included in the kit.<BR><BR>

20/25In the back, the aluminum hats needed larger holes milled to accept the 5/8-inch Strange drive studs in the 9-inch rearend. Note the safety wire securing the hat-to-rotor bolts. We did not opt for the kit with an integral, internal parking-brake mechanism, though Wilwood does offer that.<BR><BR>

BrakesWe had to think hard about our braking options, and in the end, it was clear that no one system was going to serve both our top-speed goals and our drag needs. The main issue was that we had to have 15-inch wheels to mount the best possible drag slicks, but we couldn't fit today's top-end six-piston calipers and big rotors behind the 15-inch wheels. Therefore, we knew we'd have to start with smaller street/strip brakes, then later step up to 18-inch wheels and far more serious street/track brakes once the F-Bomb's drag days are over.

We consulted Wilwood with the dilemma. It was important that the car be equipped with a reliable Stroud parachute for the dragstrip and that we wouldn't be driving 150-plus on the street. Therefore, we used a braking setup compatible with our 15-inch wheels, using 10.75-inch-front and 11.75-inch-rear rotors with Wilwood's Dynalite forged four-piston calipers. Rather than using drag-style, solid steel rotors, Wilwood recommended vented rotors for better street use and rotor cooling on this heavy car. Also, the company advised against drilled or slotted rotors, as holes and slots are mostly decorative and would provide points for cracks to begin during the cold stops associated with drag racing.

Steering and HydroboostIt's unusual for a drag car to be loaded with power steering and power brakes, but again, we were thinking long term and wanted to add these features while the car was being built the first time rather than trying to integrate them once the rollcage and turbo-plumbing fabrication were complete. We also knew that power brakes would help crutch our slightly undersized drag-race brakes before we had a chance to upgrade.

Our choice from the beginning was to use a hydroboost setup from Hydratech. Hydroboost uses hydraulic assist from the steering pump rather than vacuum from the engine to power the brake booster. This is similar to the system used on older heavy-duty trucks and on current Hummers and Mustangs. The major advantages of the system for our car were that engine vacuum/boost would not affect booster operations and that the elimination of the vacuum booster would save us a ton of space. The complete '70-'81 Camaro kit from Hydratech runs $695, minus the master cylinder of your choice but including the plumbing.

Wheels and TiresFor the first round of dragstrip use, the F-Bomb uses Mickey Thompson ET Drag wheels that we had anodized black to match the theme of the car. The wheels are 15x3.5 with 2.5-inch backspacing and 15x12 with 6.5-inch backspacing. Tires are M/T ET Fronts in 27.5x4.50-15 and ET Drags in 28x10.50-15W. Note that the W means these are extra wide. The actual measured size of the rear tires mounted on 15x12 wheels with 15 psi of air is 28 1/4 inches tall; the overall width is 14 3/8 and the measured tread width is 11 1/2 inches.

Our Strange 9-inch rearend with the Wilwood brakes installed has an overall width from wheel-mounting flange to wheel-mounting flange of 58 5/16 inches. With the tires on 15x12 wheels with 6.5-inch backspacing and with the DSE Deep Tubs in place, the tires just barely clear with about 1/4 inch before they rub the leaf springs. They're OK for drag use, but street tires will need to have less section width.

Want More F-Bomb?This story is just one part of the ongoing saga of the F-Bomb. To see the stories about the twin-turbo engine buildup, the chassis fabrication, and the paint, hit the Project Car section of www.HOTROD.com now or buy the mags at www.primediabackissues.com. You can also talk about it on the message boards of HOTROD.com.